Apparatus for partial combustion of hydrocarbon fuels



United States Patent M 3,344,834 APPARATUS FGR PARTIAL COMBUSTION 0F HYDRGCARBON FUELS Jerome Feinman, Monroeviile, Pa., and David A. Muslrat, North Madison, Ohio, assignors to United States Steel Corporation, a corporation of Delaware Filed May 26, 1965, Ser. No. 459,019 3 Qaims. (Ci. 1584) This invention relates to apparatus for the partial combustion of fuels and more particularly to producing carbon monoxide and hydrogen from carbonaceous liquid fuels such as fuel oil. In certain chemical and metallurgical processes, particularly smelting processes, a stream of hot reducing gases is required. In the conventional iron blast furnace these gases are generated by the combustion of coke and any injected fuel with the preheated air at the bottom of the furnace stack. Because the temperature of the coke reaching the tuyeres is about 3000, the air must generally be preheated to about 1500 F. to generate the high temperature necessary for the process. The gases leaving the bottom of the furnace will contain about 60% nitrogen which reduces the partial pressure of the reacting gases and imposes through-put limitations because of the increased pressure drop caused by the large volume of gases. In smelting iron ore in a conventional blast furnace it is also necessary to use stoves for heating the air and also to use a large amount of coke. These are expensive items in producing the iron.

It has been proposed to generate synthesis gas by using steam to temper the flame. However, this method has the disadvantage that the temperature of the gas produced is too low for many purposes. Another disadvantage of former processes used in the partial combustion of carbonaceous fuels is the formation of solid carbon deposits in the combustion chamber or down stream therefrom.

It is therefore an object of our invention to provide apparatus for partially combustion liquid hydrocarbons in which the produced product is at a high temperature and contains a relatively small amount of nitrogen and solid carbon.

This and other objects will be more apparent after referring to the following specification and attached drawings, in which:

FIGURE 1 is a sectional view of the burner of our invention;

FIGURE 2 is an elevation of the burner tip;

FIGURE 3 is an end view of FIGURE 2;

FIGURE 4 is an elevation of apparatus for producing iron ore according to our invention; and

FIGURE 5 is a sectional view of the apparatus of FIGURE 4.

Referring more particularly to FIGURES 1 to 3 of the drawings, reference numeral 2 indicates a combustion chamber which is lined with a highly refractory material 4 which is capable of withstanding temperatures in excess of 4000 F. High purity magnesia or zirconia are suitable for this purpose. A low conductivity insulating refractory 6 is provided on the outside of the refractory 4. An opening 8 is provided through the refractories 4 and 6 into the chamber 2 for receiving burner 10. Burner 10 includes an atomizing nozzle 12 having a fuel inlet 14 and an atomizing gas inlet 16 which are connected to conduits 18 and 20, respectively. A tubular shroud 22 having an inside diameter substantially equal to the outside diameter of nozzle 12 surrounds the nozzle 12 and the conduits 18 and and provides a chamber 23 leading to nozzle 12. The shroud 22 is made of a heat resistant metal such as Inconel or Type 310 stainless steel. A' shield 24 of similar material may be attached to the inside of shroud 22 at the outlet end thereof. A conduit 26 surrounds the shroud 22 and provides a cooling water 3,344,834 Patented Gct. 3, 1967 chamber 28. The nozzle 12 includes a member 30 which has a cylindrical portion 31 with a plurality of spiral grooves 32 therein. While eight grooves are shown the number may be greater or smaller although, for best results, there should be a minimum of one groove per quadrant equally spaced from one another. Primary oxygen passes through the grooves 32 from chamber 23 and the size of the grooves should be such to provide for a total pressure drop therethrough of at least 5 lbs. per sq. in. at the minimum oxygen rate. A nozzle tip 34 is provided at the discharge end of the nozzle 12 and consists of a body portion 38 threaded into member 30 and an outlet member 40 connected to member 38 by means of collar 42. Axial openings through members 38 and 40 are aligned with fuel inlet 14. Member 38 has a circular passage 44 which connects with gas inlet 16. Three equally spaced openings 46 lead from the passage 44 to the discharge end of member 38. The burner tip 34 may be a conventional tip which includes a standard spray nozzle such as manufactured by Spraying Systems Company of Bellwood, Illinois.

In operation, liquid fuel oil passes through conduit 18 into the nozzle tip 34 and atomizing air or oxygen passes through conduit 20 into tip 34 where the liquid fuel is atomized. At the same time, primary oxygen is introduced through chamber 23 and grooves 32 around the burner tip 34. The oxygen passing through'the grooves 32 is given a vortex or whirling action which, in addition to providing good mixing action, increases the effective residence time of the reactants in the combustion zone and results in more efiective fuel conversion so that less ungasified carbon leave the combustion zone. The minimum amount of oxygen provided through conduit 20 and chamber 23 should be the stoichiometric ratio for combustion of the fuel to carbon monoxide and hydrogen, and the maximum amount of total oxygen should not exceed approximately of this amount. Partial combustion of the liquid fuel is completed in the chamber 2 and the gases so produced will pass to the processing chamber where they will be burned to complete the process. In some instances, powdered coal may be substituted for the fuel oil.

We have found that it is essential to maintain at least a minimum atomizing-flow to liquid-flow ratio and to maintain a minimum pressure drop through the nozzle to insure that the liquid droplets are smaller than the maximum required for good performance. In the case of No. 6 fuel oil, the minimum atomizing-flow to liquid-flow ratio is about 4 standard cu. ft. of atomizing gas per lb. of oil, although this ratio might be lower at maximum capacity operation. Ratios higher than the minimum provide better operation. The minimum pressure drop through the nozzle to provide for sufficient dispersion should be about 30 lbs. per sq. in. When operating at low throughputs the minimum pressure drop for effective operation is below 30 lbs. per sq. in. Whereas at high through-puts the minimum pressure drop should be above 30 lbs. per sq. in. We have also found that the temperature of the oil and gas streams entering the system should be kept as low as possible so that the oil temperature in nozzle tip will not exceed the minimum temperature for noncoking operation. This prevents formation of coke in the tip and its resultant disadvantages. In general the oil temperature should be less than F. and the gas temperatures less than 100 F. entering the burner.

FIGURES 4 and 5 show an embodiment of our invention where the burner is used to smelt iron ore. As there shown the furnace includes a hearth 50 having a tap hole 52 which is connected by means of a frusto-conical portion 54 to a stack or reactor 56. A stationary hopper 58 is supported on top of the furnace and a portable hopper 69 is received in the top of the stationary hopper 58. A

plurality of burners discharge into the frusto-conical portion 54 through tunnels 62. Each tunnel or combustion chamber 62 is lined with a high duty refractory 64 which is preferably zirconia. The hearth 50 and reactor 56 are lined with high alumina brick 66 with a layer of fireclay brick 68 on the outside thereof. A light weight castable refractory 70 surrounds the fireclay bricks 68 to provide insulation. A steel shell 72 forms the outside surface of the furnace and is provided with means for supporting the burners 10. A gas outlet 74 is provided at the top of the furnace. With the furnace charged with coke, limestone and briquettes containing iron ore and/ or iron oxide and the burners are operated in the manner set forth above so as to smelt the iron. The partially combusted gas combines with the oxygen in the ore or other oxide. In a pilot plant operation the furnace was operated with 10% coke and 90% self fluxing iron oxide containing sinter'. In approximately 12 hours after the first charge, small amounts of molten iron were tapped and additional burden was added through the hoppers 58 and 60. Additional operation of the furnace increased the formation of molten iron which reached a steady state after several hours. The combusted'gases leave the reactor through conduit 74. It was found necessary to operate the burners entry and exit end, said tubular member having a substantially constant inside diameter for the majority of its length; a nozzle within said tubular member adjacent its exit end, said nozzle including an outer cylindrical portion closely fitting the inside of said tubular member, said cylindrical portion having at least four spiral grooves therein equally spaced around its periphery and each having an opening at each end into the inside of said tubular member, and a burner tip at its exit end of less diameter than the inside of said tubular member, said nozzle including a central axial passageway for said fuel and means for delivering an oxygen containing gas around said passageway; means Within said tubular member for separately delivering fuel and oxygen containing gas to said nozzle, and means for introducing oxygen into said tubular member and into said spiral grooves.

2. Apparatus according to claim 1 including a combustion chamber at the exit end of said. nozzle.

3. Apparatus according to claim 1 including a portion on said tubular member extending beyond the exit end of said nozzle, a shield attached to the inside of said last named portion at the end thereof, said shield having a frusto-conical axial opening therethrough with its minimum diameter at the exit end thereof, and a refractory lined combustion chamber at the exit end of said tubular member.

References Cited UNITED STATES PATENTS 1,073,438 9/1913 Potter M 15876 2,701,164 2/1955 Purchas et al. 239400 2,904,417 9/1959 Te Nuyl 239-400 X FREDERICK L. MATTESON, 1 11., Primary'Examiner.

E. G. FAVORS, Assistant Examiner. 

1. APPARATUS FOR PARTIALLY COMBUSTING NON-GASEOUS HYDROCARBON FUEL COMPRISING A TUBULAR MEMBER HAVING AN ENTRY AND EXIT END, SAID TUBULAR MEMBER HAVING A SUBSTANTIALLY CONSTANT INSIDE DIAMETER FOR THE MAJORITY OF ITS LENGTH; A NOZZLE WITHIN SAID TUBULAR MEMBER ADJACENT ITS EXIT END, SAID NOZZLE INCLUDING AN OUTER CYLINDRICAL PORTION CLOSELY FITTING THE INSIDE OF SAID TUBULAR MEMBER, SAID CYLINDRICAL PORTION HAVING AT LEAST FOUR SPIRAL GROOVES THEREIN EQUALLY SPACED AROUND ITS PERIPHERY AND EACH HAVING AN OPENING AT EACH END INTO THE INSIDE OF SAID TUBULAR MEMBER, AND A BURNER TIP AT ITS EXIT END OF LESS DIAMETER THAN THE INSIDE OF SAID TUBULAR MEMBER, SAID NOZZLE INCLUDING A CENTRAL AXIAL PASSAGEWAY FOR SAID FUEL AND MEANS FOR DELIVERING AN OXYGEN CONTAINING GAS AROUND SAID PASSAGEWAY; MEANS WITHIN SAID TUBULAR MEMBER FOR SEPARATELY DELIVERING FUEL AND OXYGEN CONTAINING GAS TO SAID NOZZLE, AND MEANS FOR INTRODUCING OXYGEN INTO SAID TUBULAR MEMBER AND INTO SAID SPIRAL GROOVES. 